Abstract: A system for filtering multiple event signals from multiple event-generating sources. A selection circuit receives the multiple event signals and selects one of the event signals. A filter circuit is coupled to the selection circuit and receives the selected event signal from the selection circuit. The filter circuit produces a filtered event signal. A counter receives the filtered event signal from the filter circuit and is incremented in response to the filtered event signal. The filter circuit includes a comparison logic circuit and an edge detection logic circuit.

Abstract: A processor having an address generation unit (AGU) for generating an address corresponding to an entry that is to be fetched. The AGU includes a segment register file for storing address segments, and a circuit for rearranging noncontiguous base and limit bit positions of a first address segment in order to generate a second address segment having all base and limit bits in a contiguous order. The AGU further includes a circuit for executing a single microinstruction to perform read and write operations on a selected field of the second address segments stored in the segment register file.

Abstract: A microprocessor comprising an execution unit for performing arithmetic functions, a fetch unit for determining which entry is to be accessed, an issue unit for accessing the entry from storage in a memory, and an address generation unit for generating an address for that entry. Portions of the base and limit values used for generating the address are stored in separate segments. These separate portions are rearranged so as to form a segment having contiguous base and limit bits. The contiguous base and limit values are then stored in a register file. Copies of the base and limit are stored in control registers and broadcast to other units. Furthermore, a resettable null bit is stored in another register. In addition, the AGU includes a means for selecting a particular field of the register file and performing read/write operations on the selected file.

Abstract: A mechanism and procedure for providing an efficient pipeline for reading and writing information to a multiple ported segment register file (SRF) in different pipestages. The present invention is operable, in one embodiment, within an address generation unit (AGU) of a processor and is implemented to write the SRF during a particular clock phase of a pipestage and to read to the SRF during another clock phase of another pipestage of the AGU pipeline of a pipelined processor. The read and write of different pipestages associated with separate instructions may occur within a same clock cycle. The write occurs before the read. By reading and writing to the AGU in alternate clock phases, the read and write operations of the SRF do not conflict even though they span different pipestages of the pipeline. Therefore, pipestages of the present invention are not in resource conflict over the SRF read and write operations which occur in a same clock cycle.